Self-locking roller cam for hose and pipe coupling

ABSTRACT

A coupling for joining conduits together is disclosed, the coupling having male and female fitting portions held in engagement by a self-locking roller cam positioned on the female portion. The roller cam has a cam body rotatable about an axis offset from the center of the cam body. An annular roller surrounds the cam body and is rotatable relatively to it. An outwardly facing surface on the roller engages an opposing concave surface on the male portion of the coupling. Reaction forces between the roller and the opposing surface operate along a line of action initially positioned to one side of the offset axis to create a torque opposing rotation of the cam into engagement with the opposing concave surface. Further forced rotation of the cam into engagement with the opposing concave surface causes the line of action of the reaction force to shift to an opposite side of the offset axis thereby creating a torque which causes rotation of the cam body into engagement with the opposing concave surface to retain the male fitting portion within the female fitting portion.

RELATED APPLICATION

This application is based on and claims the benefit of U.S. ProvisionalApplication No. 60/356,232, filed Feb. 12, 2002.

FIELD OF THE INVENTION

The invention concerns a self-locking cam having a cam surface thatrotates relatively to a cam body to reduce cam actuation force and wearbetween the cam and an opposing surface engaged by the cam surface. Theinvention is useful in quick disconnect pipe and hose couplings.

BACKGROUND OF THE INVENTION

In many industries such as mining, petroleum, construction and chemicalproduction, as well as services such as municipal water and sewerservice or emergency services, it is often advantageous to be able torapidly construct temporary piping networks for the conveyance ofpressurized fluids such as water, oil and natural gas. Since such pipingnetworks must often be constructed in the field, with few constructionfacilities available, it is preferred that the piping comprising suchnetworks be rapidly and securely connectable and disconnectablemechanically without the need for specialized tools or techniques.

To this end, mechanical couplings 10, as shown in FIG. 1, have beendeveloped. Couplings 10 have a male fitting 12 that engages a femalefitting 14, compressing a seal 15 within the female coupling. Thefittings are secured to one another by one or more cams 16 mounted onthe female fitting. Cams 16 comprise a cam body 18 that rotates about anaxis 20 offset from the cam body. The offset axis 20 permits the cambody 18 to be rotated into and out of the female fitting 14 and forciblyengage a concave surface 22 on the male fitting 12 to compress the seal15 and retain the male fitting within the female fitting. Rotation ofthe cam body is effected manually by a lever 24 that extends from thecam body. The fittings 12 and 14 may be rapidly engaged or disengaged byrotating the cam bodies into and out of engagement with the malefitting.

There are several disadvantages with prior art mechanical couplingsusing cams to secure fittings together. The disadvantages result fromthe degree of interference required between the cam body 18 and theconcave surface 22 upon engagement in order to secure the fittingstogether in a fluid-tight fit. The interference results in significantfrictional forces between the cam body and the concave surface. Thefriction causes wear of both the cam body and the concave surface asthey move relatively to one another and also results in relatively highactuation forces being required to rotate the cams by means of thelevers 24. The frictional forces and wear are further aggravated by thepresence of abrasive contaminants such as sand, mud or other particlesbetween the cams and the concave surface. The wear causes the cams andfittings to require frequent replacement, and the high actuation forcesmake it difficult to manually rotate the levers to engage or disengagethe fittings. There is clearly a need for an improved mechanicalcoupling using cams that does not suffer from high wear between therelatively moving parts or require high actuation forces for engagementand disengagement.

Another disadvantage of the prior art coupling is the lack of aself-locking feature of the cams. Unless additional locking mechanismsare employed, the cams, when closed to effect the joint, are kept in theclosed position only by the friction between the cam and concavesurface, or by special locking pins or mechanisms designed to hold thecams in place. Under vibration or shock loads, one or more of the camsmay disengage and allow leakage or separation of the pipe or hose endsunless locking features are provided.

SUMMARY AND OBJECTS OF THE INVENTION

The invention concerns a self-locking roller cam for engaging anopposing surface. The roller cam comprises a cam body having a center,the cam body being rotatable about an axis offset from the cam bodycenter. An annular roller surrounds the cam body, the roller beingrotatable relatively to the cam body and having an outwardly facingroller surface engageable with the opposing surface at a contact point.The cam body is rotatable about the offset axis to bring the rollersurface into engagement with the opposing surface. The cam body isfurther rotatable relatively to the roller to forcibly engage the rollersurface against the opposing surface in a self-locking manner.

The self-locking aspect is achieved by positioning the cam body centerrelatively to the offset axis such that a line of action passing throughboth the contact point and the cam body center initially passes to oneside of the offset axis. This creates a first torque that resistsrotation of the cam body about the offset axis in a direction moving thecam body into engagement with the opposing surface. The line of actionmoves upon further rotation of the cam body and passes to another sideof the offset axis so as to create a second torque opposite the firsttorque. The second torque causes rotation of the cam body about theoffset axis in a direction moving the cam body into engagement with theopposing surface. The second torque holds the roller surface inengagement with the opposing surface.

The invention also concerns a self-locking coupling for joining conduitends together. The self-locking coupling comprises a first fittinghaving a concave surface facing radially outwardly from one end thereof.Another end of the first fitting is adapted for attachment to one of theconduit ends. A second fitting has a receptacle at one end adapted tocoaxially receive the first fitting. Another end of the second fittingis adapted for attachment to another one of the conduit ends. A rollercam is mounted on the second fitting, the roller cam comprising a cambody having a center. The cam body is rotatable about an axis offsetfrom the cam body center. The cam body is movable into and out of thereceptacle upon rotation about the offset axis.

The roller cam further comprises an annular roller surrounding the cambody. The roller is rotatable relatively to the cam body and has anoutwardly facing roller surface engageable with the concave surface at acontact point when the first fitting is received within the receptacle.The cam body is rotatable about the offset axis into the receptacle tobring the roller surface into engagement with the concave surface at thecontact point. The cam body is further rotatable relatively to theroller to forcibly engage the roller surface with the concave surface ina self-locking manner and thereby retain the first fitting within thereceptacle.

The self-locking aspect is achieved by positioning the cam body centerrelatively to the offset axis such that a line of action which passesthrough both the contact point and the cam body center upon engagementof the roller surface with the concave surface initially passes to oneside of the offset axis. This line of action creates a first torqueresisting rotation of the cam body about the offset axis in a directionmoving the cam body into engagement with the concave surface. The lineof action moves upon further rotation of the cam body and passes toanother side of the offset axis so as to create a second torque oppositeto the first torque. The second torque causes rotation of the cam bodyabout the offset axis in a direction moving it into engagement with theconcave surface. The second torque holds the roller surface inengagement with the concave surface thereby locking the first fittinginto engagement with the second fitting.

It is an object of the invention to provide a self-locking cam.

It is another object of the invention to provide a self-locking camhaving an annular roller surrounding the cam to reduce friction andactuation forces for the cam.

It is still another object of the invention to provide a self-lockingcam which reduces wear between components moving relatively to oneanother.

It is yet another object of the invention to provide a self-locking camuseable in a coupling for connecting conduits such as hoses and piping.

It is again another object of the invention to provide a self-lockingcam wherein a shifting line of action generates torques which hold thecam in a position of engagement with an opposing surface to create theself-locking characteristics.

These as well as other objects and advantages of the invention willbecome apparent upon consideration of the drawings and the descriptionof the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional view of a mechanical pipe coupling usingcams according to the prior art;

FIG. 2 is a sectional view of a mechanical pipe coupling using rollercams according to the invention;

FIG. 2A is a cross-sectional view taken at line 2A of FIG. 2;

FIG. 3 is another sectional view of the mechanical pipe coupling shownin FIG. 2;

FIGS. 4 and 5 are detailed partial sectional views on an enlarged scaleof the mechanical pipe coupling in FIGS. 2 and 3 showing the lines ofaction of forces affecting the roller cams during rotation of the cams;and

FIG. 6 is an alternate embodiment of the mechanical pipe couplingaccording to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 shows a pipe coupling 30 according to the invention. Pipecoupling 30 includes a male fitting 32 having an end 34 adapted toengage a female fitting 36 and an opposite end 38 attachable to aconduit, for example a pipe or hose end 40. Male fitting 32 ispreferably substantially cylindrical in shape and has a concave surface41 positioned in spaced relation to end 34. Concave surface 41 facesradially outwardly and preferably extends circumferentially around thefitting as shown in FIG. 2A.

Female fitting 36 has a receptacle 42 at one end adapted to receive themale fitting 32. The other end 44 of the female fitting 36 is adapted toattach to another conduit, such as pipe or hose end 46. Preferably, aseal 48 is positioned within receptacle 42, the seal engaging both themale and female fittings to ensure a fluid-tight joint. Seal 48 ispreferably formed from a flexible, resilient material such as anelastomer. Male and female fittings 32 and 36 are preferably machinedcastings formed of a durable, high-strength metal such as aluminum,bronze, cast iron or steel. The fittings may also be formed of plasticsuch as polypropylene.

One or more self-locking roller cams 50 are mounted on the receptacle 42of the female fitting 36. Roller cams 50 each have a cam body 52 that ispreferably cylindrical and rotatable about an axis 54 offset from thecenter of the cam body. The offset axis of rotation 54 is orientedtransversely to the long axis 56 of the female fitting 36. A respectivelever arm 58 is attached to each cam body 52, the lever arm providingleverage for manually rotating the cam body about the offset axis 54.When cam bodies 52 rotate about their respective offset axes 54, theymove from a position outside of the receptacle 42, as shown in FIG. 2,to a position within the receptacle, as shown in FIG. 3. This allows theself-locking roller cams 50 to engage the concave surface 41 of the malefitting, the surface 41 acting as an opposing surface to the roller cams50 as described below.

An annular roller 60 surrounds each cam body 52. Roller 60 is rotatablerelatively to the cam body 52 about the center 62 of the cam body.Roller 60 has an outwardly facing surface 64 that is engageable with thecircumferential concave surface 41 of the male fitting 32.

To couple conduits such as pipe or hose ends 40 and 46 together in afluid-tight joint, levers 58 are moved outwardly and away from thefemale fitting 36 to rotate the roller cams 50 about respective offsetaxes 54 and into the position shown in FIG. 2. This moves the cam bodies52 out of the receptacle 42 and allows the male fitting 32 to bereceived within the receptacle so that its front face 66 may engage seal48 as shown in FIG. 3. To secure the male fitting within the receptacle,levers 58 are moved inwardly and toward the female fitting 36 to theposition shown in FIG. 3. The roller cams 50 rotate about respectiveoffset axes 54 and position the cam bodies 52 within the receptacle 42.The outwardly facing surfaces 64 of the annular rollers 60 engage theconcave surface 41 of the male fitting 32 as the cam bodies 52 are movedinto the receptacle 42. Upon engagement with concave surface 41, therollers 60 are fixed in rotation relatively to the concave surface bytheir contact with it, and the cam bodies 52 rotate relatively to theannular rollers 60 as the levers 58 are further moved to the fullyclosed position shown in FIG. 3. Allowing the cam bodies to rotaterelatively to the rollers prevents relative motion between the concavesurface 41 and the outwardly facing surfaces 64 of the of the rollers60, thus, eliminating both friction and wear of these surfaces. Anyfriction and-wear occurs between the rollers 60 and their respective cambodies 52 where the frictional forces and wear can be limited bylubricating and/or hardening the bearing surfaces between the rollersand the cam bodies. The relatively large surface area of the bearingsurfaces between the rollers 60 and the cam bodies 52 lowers the contactstresses between the cam bodies and the rollers, further resulting inreduced wear and increased life of the coupling. Wear is furthermitigated since the presence of abrasive contaminants between outwardlyfacing surface 64 and the concave surface 41 is no longer significantsince there is no relative motion between them. The reduced friction andwear between the relatively moving parts also causes a reduction in theforce needed to move the levers 58 between the open and closed positionsof FIGS. 2 and 3.

Details of the self-locking characteristics of the coupling areillustrated in FIGS. 4 and 5. The description provided below addressesonly one roller cam, it being understood that the same description ofoperation applies to each roller cam present on the coupling.

As shown in FIG. 4, male fitting 32 is received within receptacle 42 ofthe female fitting 36 and lever 58 is moved in a counterclockwise mannertoward the female fitting as indicated by arrow 70. Motion of the lever58 rotates the cam body 52 about offset axis 54 and into the receptacle42, the outwardly facing surface 64 of roller 60 engaging the concavesurface 41 of the male fitting 32 at a contact point 39, initiallypositioned adjacent to a leading edge 37 of the concave surface 41.During the phase of operation shown in FIG. 4, the front face 66 of malefitting 32 is forced against seal 48 (as shown by arrow 72) by theinteraction of the roller 60 with the concave surface 41 at the contactpoint 39. The interaction of outwardly facing surface 64 with concavesurface 41 as well as compression of the male fitting 32 against theseal 48 results in a reaction force occurring along a line of action 74that passes through the contact point 39 and the center 62 of cam body52 and to one side of offset axis 54. This creates a torque that resiststhe counterclockwise motion of the lever 58. As the lever 58 is movedfurther counterclockwise, the contact point 39 between outwardly facingsurface 64 of roller 60 and concave surface 41 moves upwardly along theconcave surface, causing increased compression of the seal 48. Thereaction force increases with increased compression of seal 48, but thetorque resisting the counterclockwise motion of the lever 58 reaches amaximum and then decreases as the line of action 74 passes through theoffset axis 54 due to the reorienting of the line of action 74 caused bythe changing position of the cam body center 62 and the contact point 39relative to the offset axis 54. This is the point of maximum sealcompression. Further counterclockwise rotation of the cam body 52 placesthe line of action 74 on the opposite side of offset axis 54 as shown inFIG. 5, relieving a small portion of the seal compression. In thisconfiguration, the reaction force operating along the line of action 74due to the interaction of outwardly facing surface 64 with concavesurface 41 as well as the compression of seal 48 now produces a torquethat operates to move lever 58 in a counterclockwise sense as shown byarrow 76. This torque tends to hold the lever in the closed positionshown in FIG. 5, thereby providing the self-locking feature that retainsthe male fitting 32 within the receptacle 42. The torque increases withincreasing pressure within the fitting, as any force tending to move themale fitting 32 out of the receptacle 42 increases the counterclockwisetorque and thereby holds the lever 58 in the closed position all themore tightly. This prevents the coupling from opening inadvertently whensubject to a shock when under pressure.

It should be noted that the self-locking action is not specificallydependent upon the presence of seal 48, but occurs as a result of theinteraction between the outwardly facing surface 64 of cam 50 and theopposing surface provided by the concave surface 41 of the male fitting12. The self-locking action is augmented whenever the front face 66 iscompressed against some surface within the receptacle 42, or internalpressure within the coupling is present which would tend to force themale and female fittings apart so that a reaction force between theconcave surface 41 and the cam 50 having line of action 74 is created.

FIG. 6 shows an alternate embodiment of a coupling 30 according to theinvention, there being roller or ball bearings 78 between the rollers 60and the cam bodies 52 to further reduce friction between the relativelymoving parts.

Self-locking pipe couplings having roller cams according to theinvention have reduced friction between the relatively moving parts.This is advantageous because wear is reduced and the forces needed tomove the levers that rotate the cams to effect a fluid-tight couplingare also reduced. Less wear means the coupling will last longer. Lowerforce required to actuate the levers means that higher seal compressionforces may be achieved while still allowing for manual lever actuation,thus allowing the couplings to withstand higher internal pressureswithout leaking. Lower lever forces also result in easier assembly ofcouplings in the field The self-locking feature ensures a reliable,fluid-tight joint without the need for additional mechanisms to hold thecams in the closed position and avoid inadvertent release of thefittings.

1. A self-locking coupling for joining conduit ends together, saidself-locking coupling comprising: a first fitting having a concavesurface facing radially outwardly from one end thereof; another end ofsaid first fitting being adapted for attachment to one of the conduitends; a second fitting having a receptacle at one end adapted tocoaxially receive said first fitting, another end of said second fittingbeing adapted for attachment to another one of the conduit ends; aroller cam mounted on said second fitting, said roller cam comprising acam body having a center, said cam body being rotatable about an axisoffset from said cam body center, said cam body being movable into andout of said receptacle upon rotation about said offset axis; said rollercam further comprising an annular roller surrounding said cam body, saidroller being rotatable relatively to said cam body, said roller havingan outwardly facing roller surface engageable with said concave surfaceat a contact point when said first fitting is received within saidreceptacle, said cam body being rotatable about said offset axis intosaid receptacle to bring said roller surface into engagement with saidconcave surface at said contact point, a line of action passing throughboth said contact point and said cam body center upon engagement of saidroller surface with said concave surface, said cam body center beingpositioned relatively to said offset axis such that said line of actioninitially passes to one side of said offset axis so as to create a firsttorque resisting rotation of said cam body about said offset axis intoengagement with said concave surface, said line of action moving uponfurther rotation of said cam body and passing to another side of saidoffset axis so as to create a second torque opposite to said firsttorque and causing rotation of said cam body about said offset axis intoengagement with said concave surface, said second torque holding saidroller surface in engagement with said concave surface thereby lockingsaid first fitting into engagement with said second fitting.
 2. Aself-locking coupling according to claim 1, wherein said first andsecond fittings are substantially cylindrical in shape.
 3. Aself-locking coupling according to claim 2, wherein said concave surfaceextends circumferentially around said first fitting.
 4. A self-lockingcoupling according to claim 1, wherein said cam body is substantiallycylindrical in shape.
 5. A self-locking coupling according to claim 1,wherein said roller is substantially cylindrical in shape.
 6. Aself-locking coupling according to claim 1, further comprising aplurality of rolling bearings positioned between said cam body and saidroller.
 7. A self-locking coupling according to claim 6, wherein saidrolling bearings comprise ball bearings.
 8. A self-locking couplingaccording to claim 1, further comprising a lever arm attached to saidcam body and extending outwardly from said receptacle, said lever armproviding leverage for manually rotating said roller cam about saidoffset axis.
 9. A self-locking coupling according to claim 8, whereinsaid lever arm is positioned relative to said cam such that rotation ofsaid lever arm about said offset axis toward said second fitting causessaid roller cam to move into said receptacle, and rotation of said leverarm away from said second fitting causes said roller cam to move out ofsaid receptacle.
 10. A self-locking coupling according to claim 1,further comprising a second roller cam mounted on said second fittingsubstantially diametrically opposite to said first roller cam.